1,4-benzodiazepin-5-ones and methods for the preparation thereof

ABSTRACT

1,4-Benzodiazepin-5-ones and methods for their preparation are disclosed. These compounds are useful as intermediates in the preparation of known and pharmacologically valuable 5substituted-1,4-benzodiazepines.

United States Patent Field et al. [4 1 July 18, 1972 [54] 1,4-BENZODIAZEPIN-5-ONES AND [56] References Cited w FOR THE PREPARATION UNITED STATES mam I 3,299,053 1/1967 Archer et al "260/2393 D [72] Inventors: George Francis Field, Arlesheim, Switzer- 3,371,085 2/1968 Reeder et al ...260/239.3 D land; Leo l-lenryk Sternbach, Upper Mont- 3,457,258 7/1969 Santilli et al. ..260/239.3 D

' Willi h Zall U C't of NJ? Jose, mm W OTHER PUBLICATIONS m1 Assignee: llolfman-La Roche Inc., Nuuey. NJ. er 1 s- Chem" pp' 1998- 2003 22 Filed: April l97l Suntilli et al. J. Org. Chem. Vol. 30, 2100 2102 1965) I vv l30M5 Santilli et al. [I] J. Org. Chem." Vol. 31, pp. 4268- 4271 Related u.s. Application om 966) [63] Continuation of Ser. No. 718,259, April 2, 1968, Pat. Pn'rrlary Examiner-Henry R. Jiles No. 3,624,073, which is a continuation-in-part of Ser. AswlanrExawnerRobert Bond 665,716, Se 6 19 7 abandone Attorney-Samuel L. Welt, Jon S. Saxe, Bernard S. Leon, William G. lsgro and Margaret C. Bogasian .260 239.3D 260 239.3 ED, 424 244, [52] US Cl l ABSTRACT [51] Int. Cl. C07d 53/06 1,4-Ben2odiazepin-5-ones and methods for their preparation I [58] Field of Search ..260/239.3 D are disclosed. These compounds are useful as intennediates in the preparation of known and pharmacologically valuable 5- substituted- 1 ,4-benzodiazepines.

' thereafter reacting the compound of formula III above with an 1,4-BENZODIAZEPIN-5-ONES AND METHODS FOR THE PREPARATION THEREOF RELATED APPLICATIONS This application is a continuation of Ser. No. 718,259 filed 5 Apr. 2, 1968 now U.S. Pat. No. 3,624,073, which in turn is a continuation-in-part of Ser. No. 665,716, filed Sept. 6, 1967, now abandoned.

SUMMARY OF THE INVENTION In accordance with this invention, we have found that pharmaceutically valuable S-substitutedl ,4-ben2odiazepines of the formula R E 2 R C\ \C=N/ H wherein A is selected from the group consisting of R R and R are selected from the group consisting of hydrogen and lower alkyl; R is selected from the group consisting of phenyl, lower alkyl substituted phenyl, an halo substituted phenyl; R and R are selected from the group consisting of hydrogen and lower alkyl; and n is an integer from I to 6,

can be prepared from l,4-benzodiazepine-5-one compounds of the formula:

wherein A, R and R are as above by first reacting a compound of the formula II above with a halogenating agent to produce a compound of the formula:

(III) wherein A, R and R, are as above and X is halogen and organo-metallic salt of a phenyl compound.

DETAILED DESCRIPTION OF THE INVENTION about one to about six carbon atoms such as methyl, ethyl,

propyl, isopropyl, butyl, isobutyl, tertiary butyl and the like. The term lower alkenyl" similarly connotes both straight and branched chain unsaturated hydrocarbon radicals having from about one to six carbon atoms, such as allyl, methyl-allyl and the like. The term halogen" as used herein includes all four halogens, i.e., iodine, bromine, chlorine and fluorine. In accordance with an embodiment of this invention, R, which is a substituent in the 7-position, is a halogen, preferably chlorine. In accordance with the preferred embodiment in this invention, R, is either hydrogen or a lower alkyl group, such as methyl or ethyl. In accordance with the preferred embodiment of this invention, R is .phenyl. When R is halophenyl, the preferred halogens are chlorine and fluorine. When R, contains the grouping C,,I-I this grouping represents a straight or branched chain alkyl group containing two or more carbon atoms. In a preferred aspect in this invention, n is either 2 or 3.

In accordance with the preferred aspect of this invention R is hydrogen. When R is lower alkyl, the preferred alkyl groups are methyl and ethyl. When R and R are alkyl groups, the preferred alkyl groups are methyl and ethyl.

In accordance with an embodiment of this invention, R, and R represent one hydrogen and one lower alkyl group. In a preferred aspect of this invention, when R, or R is lower alkyl, the preferred lower alkyl groups are methyl and ethyl. The

, methyl group is most preferred when R or R is lower alkyl.

The compound of formula II above, when A is -N( R,)- CH is prepared by reacting a compound of the formula:

wherein R and R, are as above, and R is hydrogen or lower alkyl with 2-haloethyleneamine having the formula:

wherein R is as above and X is a halogen to first form a compound of theformula:

wherein R, R R and R are as above.

The compounds of formula VI above are cyclized to form compounds of formula II above where A is N(R,)CI-I,- by reacting compounds of formula VI above with a dehydrat ing agent.

The reaction of compounds of formula IV above with compounds of formula V above to produce a compound of formula VI above is carried out in an aqueous medium. This reaction generally take places in the presence of an acid acceptor. Any conventional acid acceptor can be utilized in carrying out this reaction. Typical acid acceptors which can be utilized in accordance with this invention include sodium hydroxide, calcium hydroxide, potassium hydroxide, calcium carbonate, triethylamine, etc. Generally, in carrying out this reaction, it is preferred to utilize temperatures as high as the reflux temperature of the reaction medium. However, if desired, temperatures as low as 50C. can be utilized.

When R in formula VI above is hydrogen, compounds of formula VI can be prepared from compounds of formula IV by an alternate procedure. This procedure involves treating the mums nan compound of formula W above with ethyleneimine in the presence of an aprotic Lewis acid such as, for example, boron trifluoride, titanium tetrachloride, aluminum chloride, and the like (preferably aluminum chloride) and an inert organic solvent, for example, a hydrocarbon such as benzene, toluene, and the like, followed by treatment with an acid hydrolyzing agent. Any conventional acid hydrolyzing agent can be utilized in this reaction. Among the preferred acid hydrolyzing agents are included sulfuric acid and hydrochloric acid. ln carrying out this reaction, temperature and pressure are not critical. Therefore, this reaction can be carried out at room temperature and atmospheric pressure or at elevated temperatures and pressures.

The cyclization of compounds of formula VI to produce compounds of formula II above where A is N(R,)CH,-is carried out by dehydration. Any conventional dehydration technique can be utilized to dehydrate the compounds of formula Vl above. A typical means for dehydrating the compound of formula VI above is by subjecting the compound of formula VI above to a dehydrating agent in the presence of an organic solvent. Any conventional dehydrating agent such as thionyl chloride, acetic anhydride, phosphorus pentoxide, etc., can be utilized in accordance with this invention. The dehydration reaction can be carried out at room temperature and the dehydration of compounds of formula VI above in the presence of a dehydrating agent will proceed slowly. Since the dehydration reaction can be accelerated by heating, it is generally preferred to carry out the dehydration reaction at elevated temperatures, preferably about the reflux temperature of the solvent.

Among the compounds of formula ll above wherein A is N(R,)CH that are produced by the aforementioned dehydration of compounds of formula Vl above are compounds having the formula:

RI CHR2 CNH (II-a) wherein R is halogen, trifluoromethyl, nitro and lower alkyl; and R, and R are as above.

The compound of formula 11 above wherein A is N C[N(R,,)(R, is prepared by reacting a compound of the formula:

wherein R and R are as above with an amine having a formula:

/Ro HN Rm 7 "n H (VIII) wherein R and R are as above in the presence of an acid catalyst to form a compound of the formula:

wherein R, R R and R are as above.

The preferred organic amines corresponding to formula Vlll which are utilized in carrying out the above reaction are primary amines such as methylamine, ethylamine, isopropylamine, propylamine, butylamine, etc. A most preferred organic amine for this purpose is methylamine. While it is preferred to utilize primary amines in carrying out the aforesaid reaction, secondary amines can be utilized as well as the aforementioned primary amines. Any conventional lower alkyl secondary amine can be utilized in accordance with this invention. Among the conventional secondary amines which can be utilized are included diethylamine, dimethylamine, N,N-propylbutylamine, etc.

The l,4-benzodiazepin-2,5 diones of the formula Vll above can be converted to the 2-amino or substituted amino-1,4- benzodiazepin-S-ones of the formula ll-b above by treatment with any of the aforementioned primary or secondary lower alkyl amines, in the presence of an acid catalyst. ln carrying out this reaction any conventional acid catalyst can be utilized. Typical acid catalysts which may be utilized in carrying out this reaction include p-toluene sulfonic acid and titanium tetrachloride, among others. The conversion of the compounds of the formula Vll above into compounds of the formula ll-b above is carried out in the presence of an inert organic solvent. Any conventional inert organic solvent can be utilized in carrying out this reaction. Typical inert organic solvents which can be utilized in accordance with this invention include diethyl ether, tetrahydrofuran, benzene, hexane, pentane, ethylpropyl ether and mixtures thereof. In carrying out this reaction, temperature and pressure are not critical and this reaction can be effected at room temperature or below, and at atmospheric pressure or at elevated temperatures and/or elevated pressure. Generally, it is preferred to carry out this reaction at a temperature of from about 0C. to about 25C. While it is generally preferable to utilize these low temperatures, temperatures as high as the reflux temperature of the solvent can be utilized.

Compounds of formula ll are converted to compounds of formula III by treating the compounds of formula II above with a halogenating agent. Any conventional halogenating agent can be utilized to convert the compound of formula ll above to compounds of formula III above. Among the conventional halogenating agents which can be utilized in accordance with this invention are phosphorus oxychloride, thionyl chloride, etc. Any of the conventional chlorinating techniques can be utilized in converting the compounds of formula ll above to the compounds of formula lll above.

The reaction whereby the compounds of formula III above are converted into the compounds of formula I above is carried out by simply adding an organo-metallic salt of a cyclic compound to the compound of formula III above. This reaction should be carried out in an inert organic solvent at a temperature of from about -60C. to about 35C. While temperatures above room temperature of 35C. or temperatures below 60C. can be utilized, it is seldom advisable to utilize these extreme temperatures due to the fact that the use of these temperatures is not economical and no additional beneficial results are achieved thereby. Any conventional inert organic solvent can be utilized as the reaction medium in accordance with this invention. Included among the solvents suitable for the purpose of the present invention are hydrocarbons such as benzene, toluene, xylene and the like; chlorinated hydrocarbons, such as chlorobenzene, and the like; ethers, such as tetrahydrofuran, diethyl ether, dioxane, and the like; or any other suitable solvent.

In accordance with this invention, the organo-metalltc compound which is utilized to phenylate the compound of formula lll above can be any organo-metallic compound of a cyclic compound such as phenyl, monoalkyl-phenyl or monohalogen-substituted phenyl radical. Any conventional metallic phenyl compounds can be utilized in accordance with this invention. Typical metallic phenyl compounds include the Grignard salts, lithium salts, sodium salts, etc. Among the many organo-metallic phenyl compounds which can be utilnot limitative thereof. All temperatures are stated in degrees 5 Centigrade.

EXAMPLE 1 Preparation of 4-acetyl-7-chloro-1 ,2,3 ,4-tetrahydro- 1 -methyl- 5H-1,4-benzodiazepin-5-one A mixture of 68.5 g. (0.37 mole) of S-chloro-N-methylanthranilic acid, 51 g. (0.51 mole) of calcium carbonate, 76 g. (0.37 mole) of bromoethylamine hydrobromide and 2.5 liters of water was stirred and heated under reflux for three hours. A solution of 23.4 g. (0.26 mole) of anhydrous oxalic acid in 250 ml. of water was slowly added to the refluxing mixture. The precipitated calcium oxalate was filtered off, and the filtrate adjusted to pH 7 with concentrated ammonium hydroxide. The filtrate was then concentrated to dryness in vacuo and the residue heated on the steam bath with 400 ml. of 6N ethanolic hydrogen chloride until the residue was crystalline. Filtration gave 122 g. of N-(aminoethyl)-5-chloro-N-methylanthranilic' acid hydrochloride as a solid.

A mixture of 100 g. of this solid and 1 liter of acetic anhydride was stirred and heated under reflux for 1.5 hours and then allowed to stand for 18 hours at room temperature. The excess acetic anhydride was removed in vacuo, and the residue was treated with 1 liter of water and ice and sufficient sodium bicarbonate to make neutral. The solid was collected, 1 30 sucked dry on the filter, and triturated with hot ethanol. The ethanol solution on cooling gave 30.8 g. of 4-acetyl- 7-chloro- 1,2,3 ,4-tetrahydro-1-methyl-5H-1,4-benzodiazepin-5-one.

EXAMPLE 2 Preparation of 7-chloro-1,2,3,4-tetrahydro-l-methyl-5H-1,4- benzodiazepin-S-one A mixture of 25.25 g. (0.1 mole) of 4-acetyl-7'-chloro- 1,2,3,4-tetrahydro-1-methyl-5H-1,4-benzodiazepin-5-one, 33.3 ml. (0.1 mole) of 3N sodium hydroxide and 350 ml. of ethanol was heated under reflux for minutes and then concentrated to dryness in vacuo. The residue wastreated with 500 ml. of water, collected and washed with ethanol to give 20.2 g. of 7-chloro-l,2,3,4-tetrahydro-1-methyl-5H-1,4-

benzodiazepin-S-one.

EXAMPLE 3 dissolved in 75 ml. of tetrahydrofuran, treated with charcoal,

and sodium sulfate and filtered. This solution was added to a solution in 250 ml. of tetrahydrofuran of phenyl magnesium bromide prepared from 17.7 ml. (0.17 mole) of bromobenzene. This mixture was stirred and heated under reflux for 1 hour. It was then cooled and diluted with 400 ml.

of ether and sufficient 3N hydrochloric acid to make acid. The

aqueous phase was separated, adjusted to pH 8 with 3N sodium hydroxide and extracted three times with 200 ml. of ether.

The ether extracts were combined, washed with water and dried over sodium sulfate. The residue left on removal of the ether in vacuo was crystallized from petroleum ether to give 3.3 g. of 7-chloro-2,3-dihydro-l-methyl-S-phenyl-IH-l,4-

benzodiazepine.

EXAMPLE 4 Preparation of 4-acetyl-l ,2,3 ,4-tetrahydrol -methyl-5 H-1 ,4- benzodiazepin-S-one A mixture of g. (0.66 mole) of N-methylanthranilic acid, 91 g. (0.91 mole) of calcium carbonate, 135.8 g. (0.66 mole) of bromethylamine hydrobromide and 3.0 liter of water was stirred and heated under reflux for four hours. A solution of 59.6 g. (0.662 mole) OF anhydrous oxalic acid in 600 ml. of water was slowly added to the refluxing mixture. The precipitated calcium oxalate was filtered off, and the filtrate adjusted. to pH 7 with concentrated ammonium hydroxide. The filtrate was then concentrated to dryness in vacuo and the residue treated with 450 ml. of 6N ethanolic hydrogen chloride and 300 ml. of ether. Filtration gave N-(aminoethyl)- N-methylanthranilic acid hydrochloride as a solid.

A mixture of 108.6 g. of this solid and 1 liter of acetic anhydride was stirred and heated under reflux for 1 hour. The excess acetic anhydride was removed in vacuo, and the residue was treated with 1 liter of water and ice and sufficient sodium bicarbonate to make neutral. The solid was collected to give 58 grams of 4-acetyl-1,2,3,4-tetrahydro-l-methyl-5H- 1,4-benzodiazepin-5-one.

EXAMPLE 5 Preparation of 1,2,3 ,4-tetrahydro-1-methyl-5 H- 1 ,4- benzodiazepin-S-one A mixture of 1.7 g. (7.8 mmole) of 4-acetyl-l,2,3,4- tetrahydro-l -methyl-5H-l ,4-benzodiazepin-5-one, 2.6 ml. (7.8 mmole) of 3N sodium hydroxide and 25 ml. of ethanol was heated under reflux for 15 minutes and then concentrated to dryness in vacuo. The residue was treated with water, collected to give 1.2 g. of l,2,3,4-tetrahydro-l-methyl-SH-1,4- benzodiazepin-S-one.

EXAMPLE 6 Preparation of 2,3-dihydro-l-methyl-5- -phenyl-lH-l,4-

benzodiazepine A mixture of 4.0 g. (22 mmoles) of 1,2,3,4-tetrahydro-1- methyl-SH-l-,4-benzodiazepin-5-one and 100 ml. of phosphorous oxychloride was heated in an oil bath at 100C. for one quarter hour. The solution was concentrated to dryness in vacuo. The residue was partitioned between methylene chloride and cold saturated sodium bicarbonate solution. The methylene chloride phase was dried over sodium sulfate, filtered and concentrated in vacuo. The residue was dissolved in ether and the solution filtered through a plug of alumina using more ether to wash the plug until all of the yellow color had been removed. The ethereal eluates were combined and concentrated in vacuo to give 4.1 g. of yellow oil which was 5- chloro-2,3-dihydro-1-methyl-lH-1,4-benzodiazepine. This oil was dissolved in 50 ml. of tetrahydrofuran and added slowly to a solution of phenyl magnesium bromide prepared from 17.7 ml. (0.17 mole) of bromobenzene in 250 ml. of tetrahydrofuran. This solution was stirred and heated under reflux for 1 hour. lt was then cooled and diluted with ether and 3N hydrochloric acid until the aqueous phase was acidic. The aqueous phase was separated, made alkaline with 3N. sodium hydroxide and extracted with ether. The ether was dried, filtered and concentrated in vacuo to leave a reddish oil. This oil was dissolved in ether and the solution was saturated with hydrogen chloride and the mixture --was allowed to stand for two days at room temperature. The ether was decanted from a heavy oil, and this oil was treated with ether and dilute sodium hydroxide. The ether extract was dried, filtered and concentrated in vacuo to give 4.0 g. of oil. This oil was dissolved in hexane, and the solution poured through a plug of alumina. Ether was used to continue the elution. The hexane eluates were concentrated to dryness to give 1.3 g. of 2,3-dihydro-lmethyl-S-phenyl-lH-l,4-benzodiazepine. From the ether eluates a further 1.3 g. of the product was obtained.

EXAMPLE 7 7 8 Preparation of 7-Chloro-2-methylamino-S-phenyl-3l-l-l,4- wherein R is as above and X is a halogen to form a subbenzodiazepine stituted aniline of the formula A mixture of 4.5 g. (20 mmole) of 7-chloro-3,4dihydro-2- methylamino-SH-l,4-benzodiazepin-5-one and I ml. of phosphorus oxychloride was heated under reflux overnight.

and concentrated in vacuo. Twice toluene was added to the R residue and distilled out in vacuo. The residue was dissolved in fi 0m 200 ml. of dry tetrahydrofuran and added during minutes to a solution of phenyl magnesium bromide in 500 ml. of 10 P tetrahydrofuran prepared from 3.9 g. (0.16 mole) of magnesiwhefem h 2 and s are s above and reacting said subum and 17.7 ml. (0.17 mole) of bromobenzene. The reaction amlme complund a dehydraung agent- 2. The process of claim 1 wherein said dehydrating agent is acetic anhydride.

3. A process for producing a 5-keto benzodiazepine compound of the formula:

mixture was then stirred and heated under reflux for 4 hours. It was then cooled and diluted with methylene chloride and saturated sodium bicarbonate solution. Glacial acetic acid was added until the precipitate dissolved. The organic layer was separated, dried over sodium sulfate and concentrated in vacuo. The residue was crystallized from acetone to give the above titled product, m.p. 235-240. Recrystallization from acetone gave yellowish prisms, m.p. 242-244, undepressed R on admixture with authentic material. Thin layer chromatography and infrared spectra also demonstrated identity with I authentic material.

The above starting material can be prepared by cooling a suspension of 8.4 g. (40 mmole) of 7-chloro-l,3-dihydro-2H- wherein R is selected from the group consisting of l,4-benzodiazepin-2,5(4H)-dione in 1.5 liters of tetrahydrofuhydrogen, halogen, nitro, trifluoromethyl, and lower alran to 10 and bubbling in methylamine for one-quarter hour. kyl; RI i5 Selected fr m the group consisting of hydrogen, During 15 minutes a solution of 6 ml. (46 mmole) of titanium lower y lower alkenyl and tetrachloride in 100 ml. of benzene was added to the stirred R suspension held at 10. The reaction mixture was then heated under reflux for 2 hours. After it had been cooled, 60 ml. of i ice water was added, and the precipitate filtered off. The ("11- trate was dried over sodium sulfate and concentrated in R2 R5 and R6 are sel'eted h consisting of vacuo. The residue was treated with tetrahydrofuran and hydrogen and lower alkyl; and n is an integer from 1 {06mm petroleum ether to give 7-chloro-3,4-dihydro-2-methylaminoa Substituted aniline compound of the formuIa SH-l,4-benzodiazepin-5-0ne, m.p. 225-230. Recrystallization from methanol gave colorless prisms, m.p. 246-249 (doc).

We claim: 40 N-OH H-NK, l. A process for preparing a compound of the fonnula: R

' OR: R, I l-CH1 wherein R, R and R are as above and R is hydrogen or R CHR1 lower alkyl comprising treating said substituted aniline v compound with a dehydrating agent.

CN I 4. The process of claim 3 wherein said dehydrating agent is phosphorous pentoxide.

0 5.Aprocessforpreparingacompound of the formula: wherein R [5 selected from the group consisting of hydrogen, halogen, nitro, trifluoromethyl and lower alkyl; R is selected from the group consisting of hydrogen, lower alkyl, lower alkenyl and R R and R are selected from the group consisting of hydrogen and lower alkyl; and n is an integer from 1 to 6 from an anilinecompoundoftheformula: V

wherein R 18 selected from the group consisting of R1 hydrogen, halogen, nitro, trifluoromethyl and lower alkyl; and R R, and R are selected from the group consisting NH of hydrogen and lower alkyl comprising reacting a com- R pound of the formula:

-CORa 0 wherein R and R are as above and R is a hydrogen or lower iii alkyl comprising treating said aniline compound with a 2- H halo-ethylene-amine having the formula: R

wherein R and R are as described above with a compound of the formula /Ro IIN C-N g H wherein R is selected from the group consisting of hydrogen, halogen, nitro, trifluoromethyl and lower alkyl; and R R and R are selected from the group consisting of hydrogen and lower alkyl. 

2. The process of claim 1 wherein said dehydrating agent is acetic anhydride.
 3. A process for producing a 5-keto benzodiazepine compound of the formula:
 4. The process of claim 3 wherein said dehydrating agent is phosphorous pentoxide.
 5. A process for preparing a compound of the formula:
 6. The process of claim 5 wherein the acid catalyst employed is selected from the group consisting of p-toluene-sulfonic acid and titanium tetrachloride.
 7. A compound of the formula: 